Padlock with tamper alarm

ABSTRACT

A padlock comprising a body and shackle, the shackle having an end releasably securable in the body, the body having a casing, the casing housing a tamper alarm means and a lock means, the tamper alarm means including a power supply means, the casing having an aperture configured and arranged to receive the end of the shackle being securable in the aperture by way of the lock means, a portion of the casing being movable to enable access to the power supply means, movement of the portion of the casing being prevented by a retaining means which is only accessible for insertion or removal via the aperture in the casing configured and arranged to receive the end of the shackle.

TECHNICAL FIELD

This invention relates to a padlock, and more particularly, to a padlockwhich incorporates a tamper alarm.

BACKGROUND ART

Padlocks are typically used for securing possessions, such as bicycles,trailers etc against theft whilst their owners are absent, or forpreventing unauthorised access to particular areas or locations.

However, padlocks generally do not present a significant barrier to aperson seriously intent on theft or trespass. In this regard, even amoderately well equipped thief or trespasser usually possesses thewherewithal to sever or force the shackle of the padlock.

There are a number of known padlocks which include an integral alarmsystem adopted to sound or activate when the padlock is violated ortampered with. Representative of such prior art padlocks are thosedecribed in U.S. Pat. No. 3,993,987, 4,556,872 and 4,811,578.

All of the padlocks disclosed in the above U.S. Patent Specificationsinclude an audible alarm sounding device, a battery for energizing theaudible alarm sounding device and an electrical circuit having switchesconnecting the audible alarm sounding device to the battery foractuation when the padlock is tampered with or violated. A problemassociated with all battery operated equipment is that the battery orbatteries eventually wear out and, if use of the alarm function is tocontinue, must be replaced.

The padlocks described in the above noted U.S. Patent Specificationseach include provision for access to the battery housed within thepadlock body to enable removal and replacement. In each, however, suchprovision affords an obvious point at which to gain unauthorised accessto the battery, remove it and thereby deactivate or disable the alarm.

It is an object of the present invention to provide a padlockincorporating a tamper alarm having features which reduce to at leastsome extent, as compared with the prior art, the opportunity forunauthorised deactivation of the tamper alarm.

SUMMARY OF THE INVENTION

In a broad aspect this invention provides a padlock comprising a shackleand a body, the shackle having an end releasably securable in the body,the body having a casing, the casing housing a tamper alarm means and alock means, the tamper alarm means including a power supply means, thecasing having an aperture configured and arranged to receive the end ofthe shackle, the end of the shackle being securable in the aperture byway of the lock means, a portion of the casing being movable to enableaccess to the power supply means, movement of the portion of the casingbeing prevented by a retaining means, characterised in that theretaining means is only accessable for insertion or removal via theaperture in the casing configured and arranged to receive the end of theshackle.

Preferably, the casing comprises two or more portions maintained incontiguity by the retaining means.

Desirably, the casing portions can interlock.

Optionally, the shackle is entirely separable from the body. In whichsituation the interlocking sections of the casing can be maintained inreleasable interlocked engagement by way of a first and a secondretaining means both locatable interior of the casing, the firstretaining means only being accessable when interior of the casingthrough a first aperture in the casing, the first aperture beingconfigured and arranged to receive a first end of the shackle, and thesecond retaining means only being accessable when interior of the casingthrough a second aperture in the casing, the second aperture beingconfigured and arranged to receive a second end of the shackle, both thefirst end and the second end of the shackle being releasably securablewithin the casing by way of the lock means.

Alternatively the shackle can have a first end and a second end, thefirst end being releasably securable in the aperture in the casing, andthe second end being captively mounted within or to the body.Expediently the second end can be fixed mounted to the body.

The shackle may be of any known type, including both rigid type andflexible shackles, examples of the latter being those formed from chainor cable.

Further, the lock means may similarly be of any known type.

Preferably, the shackle is a rigid U-shaped member.

Desirably, the shackle forms part of the electrical circuit of thetamper alarm means and can be provided with an electrically insulativecoating to facilitate this function.

BRIEF DESCRIPTION OF THE DRAWINGS

Two presently preferred embodiments of the invention will now bedescribed, by way of example only, with reference to the accompanyingdrawings, in which:

FIG. 1 illustrates a partially cut away front elevation of a padlock inaccordance with the present invention;

FIG. 2 illustrates a partially cut away side elevation of the padlock ofFIG. 1;

FIG. 3 illustrates a plan view of the padlock of FIG. 1;

FIG. 4 illustrates a sectional front elevation of part of the padlock ofFIG. 1;

FIG. 5 illustrates a perspective view of the padlock of FIG. 1;

FIG. 6 illustrates a partially cut away front elevation of analternative padlock in accordance with the present invention;

FIG. 7 illustrates a front elevation of the shackle of the padlock ofFIG. 6;

FIG. 8 illustrates a plan view of the padlock of FIG. 6; and

FIG. 9 illustrates a sectional front elevation of part of the padlock ofFIG. 6.

FIGS. 1 to 5 of the drawings illustrate a first embodiment of theinvention, namely, a padlock, as generally indicated at 1, incorporatinga tamper alarm. The padlock 1 comprises a body 2 and a shackle 3.

The shackle 3 is a rigid U-shaped member having a short leg 4 and a longleg 5. The short leg 4 terminates at a first end portion 6 and the longleg 5 terminates at a second end portion 7 which is adapted to bepermanently housed within the body 2.

The body 2 includes an outer casing 8 formed as two interlockablesections 8a and 8b. The sections 8a and 8b are substantially symmetricalin shape and appearance and are maintained in interlocked engagement byway of a retaining pin 9. In addition to the retaining pin 9 a pluralityof lugs 10 are provided on the interior mating face of each section 8a,8b which, when the sections 8a, 8b are brought together, slidablyinterlock thereby providing a firm secure connection over all areas ofcontact between the sections 8a, 8b.

The retaining pin 9, which is elongate and terminates in a threadedportion 11, links and retains the sections 8a and 8b in interlockedengagement by way of pairs of lugs 12, one lug 12 on each pair being oneach section 8a/8b. Each lug 12 has an aperture 13 therethrough sized toaccommodate the pin 9. The apertures 13 of the various lugs 12 arealigned so that the pin 9 may extend continuously therethrough.

The threaded portion 11 of the pin 9 is screwed into a locking nut 14which is seated into a recess in each of the sections 8a and 8b. Accessto the pin 9 is only possible by way of an aperture 15 in the casing 8,which aperture 15 is sized to snuggly receive the end portion 6 of theshort leg 4 of the shackle 3.

The shackle 3 is mounted so as to permit reciprocal movement relative tothe body 2 between a closed, depressed position, in which end portions6,7 of both legs 4,5 are in the body 2, the end portion 6 being in theaperture 15, and an extended, open position in which the end portion 6of the short leg 4 is outside the body 2.

A latch mechanism 16, interior of the casing 8, engages a shaped recess17 in the end portion 6 of the leg 4 of the shackle 3 when the shackleis in the depressed, closed position, thereby preventing the shackle 3from moving.

A lock arrangement 18, preferably key operated as shown in FIG. 1, isprovided to activate the latch mechanism 16 so as to release the shackle3 and allow it to move to the open position. In the open position theshackle 3 may pivot about the long leg 5. The shackle 3 is biasedtowards the open position by a spring 19.

A tamper alarm 20 is incorporated into the padlock 1 and is housedentirely within the casing 8. The tamper alarm 20 comprises a powersupply 21, for example, a 9 volt battery, an alarm sounding device 22,and an electrical circuit.

The electrical circuit may generally be considered as comprising twoportions, the first portion being the control circuitry (not shown) andthe second portion being the tamper sensing circuitry.

The spring 19 and shackle 3 form part of the tamper sensing circuitry.Electrical shielding of these components from the body 2 of the padlock1 is required, and in this connection the spring 19 is sheathed withinan insulating sleeve 23 and the shackle 3 is coated with a hard wearingelectrically insulative material over substantially its entire surface,save at ends 6,7. To close the tamper sensing circuitry a switchconnection 24 is provided adjacent the aperture 15 in the casing 8 whichis completed when contacted by the unshielded end 6 of the short leg 4of the shackle 3.

Enabling and disenabling of the tamper alarm 20 may ultimately only beeffected by way of the lock arrangement 18.

In the following description of the operation of the padlock 1 andtamper alarm 20 the alarm sounding device 22 will be referred to asemitting an audible signal. However, as will be appreciated, the alarmsounding device 22 could equally well emit an inaudible signal in theform of a radio or microwave transmission which may be received at someremote location to activate a visual indicator, such as a flashinglight, an audible indicator, such as an alarm or horn, or a combinationof these two possibilities.

In use, the padlock 1 is mounted in position to secure the desiredarticle of property or area. To achieve this the shackle 3 is depressedto the closed position, whereat the latch mechanism 16 engages theshaped recess 17 in the end portion 6 of the leg 4. In moving to theclosed position the end portion 6 closes the tamper sensing circuitry bycompleting the switch connection 24. As a test feature of the status ofthe power supply 21 the alarm sounding device 22 desirably emits a shortbeep or some other such indication each time the switch connection 24 ismade.

If the padlock 1 is substantially interferred with, for example byattempting to sever the shackle 3 or prise it open, the tamper sensingcircuitry will indicate to the control circuitry and the alarm soundingdevice 22 will begin emitting an audible signal.

A second embodiment of the invention is illustrated in FIGS. 6 to 9 ofthe drawings. In these drawings a padlock, as generally indicated at100, is provided which incorporates a tamper alarm. The padlock 100comprises a body 102 and a shackle 103.

The shackle 103 includes three identifiable regions.

A central portion 104 for wrapping or placing around or through anobject to be secured, and end portions 105 and 106. The end portions 105and 106 are substantially identical, each having a first section 107 ofparticular cross-section, a second section 108 of stepped downcross-section and a third section 109 adapted to co-operate with meansfor locating and retaining the shackle 103 within the body 102.Preferably, both the first and second sections, 107 and 108respectively, are circular in cross-section, although it will beappreciated that this need not be so by necessity and indeed a square orrectangular cross-section could be adopted. The third section 109 mayconveniently comprise a groove 110 around the circumference of the endportion 105,106 in the second section 108. Again, however, other formsare envisaged, such as, for example, a notch or aperture extending in orthrough the second section 108.

In the drawings the shackle 103 is shown as having a central portion 104which is rigid and U-shaped, so that the shackle 103 as a whole is rigidand U-shaped. However, alternatives, such as flexible wire or chaincould equally well be used, and in some applications would bepreferable.

The body 102 includes an outer casing 111 formed as two interlockablesections 111a and 111b. The sections 111a and 111b are substantiallysymmetrical and identical in outward shape and appearance and aremaintained in interlocked engagement by way of a pair of retaining pins112.

The retaining pins 112, which are elongate and terminate in a threadedportion 113. Each retaining pin 112 links and retains the sections 111aand 111b in interlocked engagement by way of two pairs of lugs 14, onelug 114 on each pair being part of each section 111a/111b. Each lug 114has an aperture 114 therethrough sized to receive and accommodate thecorresponding pin 112. The apertures 115 of each of the four lugs arealigned so that the corresponding pin 112 may extend therethrough. Thethreaded portion 113 of each pin 112 is screwed into a locking nut (notshown) which is seated into a recess in each of the sections 111a and111b. Access to each pin 112 is only possible by way of a correspondingaperture 116 in the casing 111. The apertures 116 are sized to snugglyreceive one or other of the end portions 105,106 of the shackle 103.

A latch mechanism 117 is provided interior of the casing 111 toreleasably engage and retain the end portions 105 and 106 of the shackle103 when inserted into the apertures 116.

The latch mechanism 117 includes a lock arrangement 118, preferably keyoperated as shown in FIG. 1, to activate engagement and disengagement ofthe latch mechanism 117 with the end portions 105 and 106 of the shackle103.

Operation of the lock arrangement 118 causes a cam 119, rotatablymounted thereon, to rotate. The cam surface 120 of the cam 119 acts on apair of ball bearings 121. Rotation of the cam 119 causes the ballbearings 121 to move between a first position and a second position, orvice versa. With the end portions 105,106 of the shackle 103 located inthe corresponding apertures 116 of the body 102, and with the ballbearings 121 causes to move into the final position each ball bearing121 is engaged with the groove 110 in the corresponding end portion105,106, thereby locking it in position.

In the second position the ball bearings 121 can move back out of thegroove 110 to allow the end portions 105, 106 to be removed.

Positioning of the groove 110 on each of the shackle end portion 105,106relative to its corresponding ball bearing 121 is achieved utilizing thestep down in cross-sectional dimension from the first section 107 to thesecond section 108; the step bears on the outside of the body 102adjacent the aperture 116 thereby providing a location.

A tamper alarm 122 is incorporated into the padlock 100 and is housedentirely within the casing 111. The tamper alarm 122 comprises a powersupply 123, for example in the form of a 9 volt battery, an alarmsounding device 124, and an electrical circuit.

The electrical circuit may generally be considered as comprising twoportions, the first portion being the control circuitry (not shown) andthe second portion being the tamper sensing circuitry.

The shackle 103, which is made from a strong and tough electricallyconductive material, such as brass or stainless steel, forms part of thetamper sensing circuitry. Electrical shielding of this component fromthe body 102 of the padlock 100 is required, and in this connection aninsulating sleeve 125 is provided for each aperture 116 to separate theend portions 105,106 of the shackles 103 from the body 102. The shackle103 itself may be coated with a hard wearing electrically insulativematerial over substantially its entire surface, save at end portions105,106. However, because the power drawn by the tamper sensing circuitis so low it has been noted that a special insulative coating is notalways necessary, and indeed weathering of the shackle 103 to create athin oxide outer layer is often sufficient to satisfy any requirementsin this regard. To close the tamper sensing circuitry a switchconnection 126 is provided adjacent each aperture 116 in the casing 111which is completed when contracted by end portions 105,106.

Enabling and disenabling of the tamper alarm 122 may ultimately only beeffected by way of the lock arrangement 118. Preferably, the key cannotbe removed without enabling the tamper alarm 122.

In the following description of the operation of the padlock 100 andtamper alarm 122 the alarm sounding device 124 will be referred to asemitting an audible signal. However, as will be appreciated and as notedabove in respect of the first preferred embodiment, the alarm soundingdevice 124 could equally well emit an inaudible signal in the form of aradio transmission which may be received at some remote location toactivate a visual indicator, such as a flashing light, an audibleindicator, such as an alarm or horn, or a combination of these twopossibilities.

In use, the padlock 100 is mounted in position to secure the desiredarticle of property or area. To achieve this the end portion 105,106 ofthe shackle 103 are inserted into the apertures 116, whereafter thelatch mechanism 117 can be engaged and the key removed. As with thepreviously described embodiment, as a test feature of the status of thepower supply 123 the alarm sounding device 24 desirably emits a shortbeep or some other such indication each time the switch connections 126are made. If the padlock 100 is substantially interferred with, forexample by attempting to sever the shackle 103 or prise it open, thetamper sensing circuitry will indicate to the control circuitry and thealarm sounding device 124 will begin emitting an audible signal.

Referring now to both preferred embodiments, the control circuitry isdesirably designed such as to ensure that even if the tamper sensingcircuitry is recompleted, for example by utilising auxiliary wiring, theaudible alarm signal will continue to be emitted either for apredetermined time period, until the power supply fails, or untildisabled by an authorised person using the lock arrangement.

There are at least two features of the preferred embodiments whichprovide significant advantage. Firstly, with the shackle itself formingpart of the electrical circuit any severing thereof will result in thealarm sounding device generating an alarm signal. Secondly, the outsideof the padlock is specifically designed so as to be symmetrical inappearance. The net effect of this is that it is not obvious where thevarious components of the tamper alarm lie within the casing. Thereforeattempting to break into the padlock to disable the alarm will takeextra time during which, of course, the alarm sounding device willgenerate an audible alarm signal.

When the alarm sounding device 22(124) is of a form which emits anaudible signal, a grill 25(127) may be provided to maximise the volumeof signal heard. Desirably, there is provided an accousticallytransparent membrane (not shown) over the interior surface of the grill25(127) to prevent entry of a liquid which might otherwise disable thetamper alarm 20(122). Further in this connection, the various componentsof the tamper alarm 20(22) should be encased in waterproof material suchas a putty or like substance.

Additional advantages of the present invention will become apparent tothose skilled in the art after considering the principles in particularform as discussed and illustrated.

Accordingly, it will be appreciated that changes may be made to theabove described embodiment of the invention without departing from theprinciples taught herein.

In this connection, the casing need not separate symmetrically intoportions and, further, the portions may screw or twist lock togetherinstead of using lugs, the retaining means preventing untwisting.Furthermore, the casing may be of any appropriate shape.

Moreover, the second end of the shackle may be fixed, mounted to thebody, and possibly at a different face of the body from that of thefirst shackle end.

Finally, it will be understood that this invention is not limited to theparticular embodiment described or illustrated, but is intended to coverall alterations, additions or modifications which are within the scopeof the appended claims.

I claim:
 1. A padlock comprising a shackle and a body, the shacklehaving an end releasably securable in the body, the body having a casingwhich is divided into two portions, each of which comprisessubstantially half the casing, the casing housing a tamper alarm meansand a lock means, the tamper alarm means including a power supply means,the casing having an aperture configured and arranged to receive the endof the shackle, the end of the shackle being securable in the apertureby way of the locking means, one of the casing portions being removableto enable access to the power supply means, the removable portion beingheld in place by a retaining means, the retaining means only beingaccessible for retaining or releasing the removable portion of thecasing via the aperture in the casing configured and arranged to receivethe end of the shackle, the removable portion of the casing beingconfigured and arranged so as to avoid indicating the location withinthe padlock body of the power supply means.
 2. A padlock according toclaim 1, wherein the shackle has a first end and a second end, the firstend being releasably securable in the aperture in the casing, and thesecond end being captively mounted within or to the body.
 3. A padlockaccording to claim 1, wherein the shackle is a substantially flexiblemember having a first end and a second end, the first end beingreleasably securable in the padlock body and the second end is fixedmounted to the padlock body.
 4. A padlock according to claim 1, whereinthe casing portions are interlocking and are maintained in contiguity bythe retaining means.
 5. A padlock according to claim 4, wherein thecasing is substantially symmetrical.
 6. A padlock according to claim 1,wherein the tamper alarm means includes tamper sensing circuitry, andwherein the shackle is formed from an electrically conductive materialand comprises part of said tamper sensing circuity.
 7. A padlockaccording to claim 6, wherein the shackle is coated, save at its end, inan electrically insulative material.
 8. A padlock according to claim 6,wherein the camper alarm means further includes control circuitry and asignal generator to generate an alarm signal, such that when the tampersensing circuitry has sensed tampering with the padlock the controlcircuitry generates an alarm signal, the alarm signal being either anaudible signal, a radio signal, or a microwave transmission.
 9. Apadlock according to claim 1, wherein the tamper alarm means issubstantially encased in a water proof material.
 10. A padlock accordingto claim 9, wherein the signal generator emits the alarm signal througha grill in the casing, which grill is covered over its interior surfacewith an acoustically transparent membrane.
 11. A padlock comprising ashackle and a body, the shackle having first and second ends releasablysecurable in the body, the body having a casing which is divided intotwo portions, each of which comprises substantially half the casing, thecasing housing a tamper alarm means and a lock means, the tamper alarmmeans including a power supply means, the casing having an apertureconfigured and arranged to receive the first end of the shackle, thefirst end of the shackle being securable in the aperture by way of thelocking means, one of the casing portions being removable to enableaccess to the power supply means, the removable portion being held inplace by a retaining means, the retaining means only being accessiblefor retaining or releasing the removable portion of the casing via theaperture in the casing configured and arranged to receive the first endof the shackle, the removable portion of the casing being configured andarranged so as to avoid indicating the location within the padlock bodyof the power supply means.
 12. A padlock according to claim 11, whereinthe casing is substantially symmetrical.
 13. A padlock according toclaim 11, wherein the removable portion of the casing is held in placeby a first and a second remaining means, both located interior of thecasing, the first retaining means only being accessible when interior ofthe casing through a first aperture in the casing, the first aperturebeing configured and arranged to receive the first end of the shackle,and the second retaining means only being accessible when interior ofthe casing through a second aperture in the casing, the second aperturebeing configured and arranged to receive the second end of the shackle,both the first end and the second end of the shackle being releasablysecurable within the casing by way of the lock means.
 14. A padlockaccording to claim 3, wherein the casing portions are interlocking, andare maintained in contiguity by the retaining means.
 15. A padlockaccording to claim 11, wherein the tamper alarm means includes tampersensing circuitry, and wherein the shackle is formed from anelectrically conductive material and comprises pare of said tampersensing circuitry.
 16. A padlock according to claim 15, wherein theshackle is coated, save at its end, in an electrically insulativematerial.
 17. A padlock according to claim 15, wherein the tamper alarmmeans further includes control circuitry and a signal generator togenerate an alarm signal, such that when the tamper sensing circuitryhas sensed tampering with the padlock the control circuitry willgenerate an alarm signal, wherein the alarm signal is either an audiblesignal, a radio signal, or microwave transmission.
 18. A padlockaccording to claim 11, wherein the tamper alarm means is substantiallyencased in a water proof material.
 19. A padlock according to claim 18,wherein the signal generator emits the alarm signal through a grill inthe casing, which grill is covered over its interior surface with anacoustically transparent membrane.
 20. A padlock comprising a shackleand a body, the shackle having an end releasably securable in the body,the body having a substantially symmetrical casing which is divided intotwo portions, each of which comprises substantially half the casing, thecasing housing a tamper alarm means and a locking means, the tamperalarm means including a power supply means, the casing having anaperture configured and arranged to receive the end of the shackle, theend of the shackle being securable in the aperture by way of the lockingmeans, one of the casing portions being removable to enable access tothe power supply means, the removable portion being held in place by aretaining means, the retaining means only being accessible for retainingor releasing the removable portion of the casing via the aperture in thecasing configured and arranged to receive the end of the shackle, theremovable portion of the casing being configured and arranged so as toavoid indicating the location within the padlock body of the powersupply means.